Flexible Manipulators (FMs) provide a number of benefits, containing reduced weight due to the thinness of the robot’s linkages. Although the initial plan was to use actual robots’ flexibility or slenderness to their advantage, the complex dynamics of the systems piqued interest in using an experimental flexible manipulator as a testing ground for various modeling or control strategies. A review is essential for researchers who want to align their study objectives with those of the field because the literature is extensive and diverse. Due to the widespread usage of flexible manipulators in different mechatronic and robotic applications over the past few decades, many academics worldwide are now interested in researching this topic. Studies are categorized here according to the control and modeling technologies of flexible manipulators and methodologies. Review of recent works on analysis, modeling, mechanical vibration, control algorithms, gyroscope technology and applications, difficulties in managing flexible manipulators and their anticipated future, and the majority of the notable evolutionary and optimization algorithms, including Genetic Algorithm (GA), Differential Evolution (DE), and Fuzzy Logic (FL), as well as modification approaches and techniques, are discussed and underlined. This study examines many publications, thoroughly reviewing the analytical, mathematical, dynamical modeling, mechanical vibration control techniques and most of the notable evolutionary and optimization algorithmic approaches of Robotic Flexible Manipulator (RFM) structures.
53Adaptive nonlinear vibration control of a Cartesian flexible manipulator driven by a ballscrew mechanism
Adaptive nonlinear vibration control of a Cartesian flexible manipulator driven by a ballscrew mechanism
6Nonlinear partial differential equation modeling and adaptive fault‐tolerant vibration control of flexible rotatable manipulator in three‐dimensional space
SummaryIn this article, we investigate the problem of nonlinear modeling and adaptive boundary vibration control with actuator failure for a flexible rotatable manipulator in three‐dimensional space, which is made up of a rotatable base and a flexible manipulator. In order to accurately reflect the characteristics of the distributed parameters, the Hamilton principle is introduced to derive the dynamic model expressed by partial differential equations (PDEs). Based on the model, an innovative boundary control scheme is proposed to eliminate the deflection and vibration simultaneously, and to guarantee that the rotatable base and the flexible manipulator can track the desired angle respectively. The adaptive law is developed to estimate the loss of the actuator. The effectiveness of the designed controller is verified from both theoretical analysis and numerical simulation.
Read more2A Survey of Experiments for Modeling Verification and Control of Flexible Robotic Manipulators
The task of model verification and control implementation for flexible multi-body systems undergoing large-angle displacement can probably be best accomplished using the experiments involved with large flexible multi-link manipulators. In this paper, various kinds of experiments for modeling and control for large flexible manipulators are reviewed. Although most experiments are restricted to either vertical or horizontal planes, and control algorithms are applied to simplified examples, insight gained in this survey will be useful to the advancement of the state-of-the-art for accurate modeling and precision control of flexible multibody manipulators.
Read more1Dynamic modeling and adaptive control of a single-link flexible manipulator
This paper presents an application of model reference adaptive control to the position and vibration control of a single-link flexible manipulator. A distributed mass model of the flexible link has been analyzed using the method of modal expansion. The performance of the system with various control schemes has been investigated. It has been demonstrated that effective position/vibration control of a flexible manipulator is achieved by model reference adaptive control.
Read more1Soft computing approaches for control of a flexible manipulator
The aim of this chapter is to show the effectiveness of soft computing in the design of adaptive controllers for a single-link, flexible manipulator. The first part utilizes fuzzy logic (FL) and genetic algorithms (GAs) in the design of an offline modular neural network controller while the second part combines fuzzy logic and GAs in the construction of online proportional derivative (PD), proportional, integral (PI) and proportional, integral, derivative (PID)-type FL controllers. Experimental results, demonstrating the effectiveness of the methods for an experimental single-link, flexible manipulator are presented and discussed.
Read more5Adaptive control and state error prediction of flexible manipulators using radial basis function neural network and dynamic surface control method.
This paper introduces a novel control strategy for managing the uncertainties in flexible joint manipulators, incorporating a Radial Basis Function Neural Network (RBFNN) with Adaptive Dynamic Surface Control (ADSC). This strategy innovatively utilizes RBFNN to precisely approximate uncertain system dynamics and integrates a nonlinear damping term to effectively counteract external disturbances, enhancing the overall control accuracy. We have also developed an adaptive law that updates neural network weights and system parameters in real-time, ensuring the system's adaptability to dynamic changes. The application of the Lyapunov method ensures that all signals within the closed-loop system remain semi-globally uniformly bounded, significantly reducing tracking errors. Moreover, we introduce the use of Long Short-Term Memory (LSTM) networks for predictive analysis of state data, which further confirms the robustness and effectiveness of our control method through extensive simulations. The distinctive integration of these technologies and their practical validation through comparative simulations underscore the innovative aspects of our approach in addressing real-world challenges in flexible manipulators.
Read more10Tip position control of a two-link flexible robot manipulator based on nonlinear deflection feedback
Tip position control of a two-link flexible robot manipulator based on nonlinear deflection feedback
<title>Experiments in control of flexible beam with modified outputs</title>
This paper presents new experimental results which pertain to the control of flexible link manipulators. Flexible link manipulators have the peculiar characteristic of possessing an infinite number of degrees-of-freedom, but (usually) only one actuator per link. This is one of the main distinctions, along with the presence of significant kinematically induced nonlinearities, between flexible manipulator control and control of other flexible bodies such as large spacecraft. For such systems, one safe and reliable strategy is to maximize the modal damping. To increase the system modal damping one can use feedback control and in particular this paper reports results of feedback control experiments which use modified outputs as the feedback signal. These outputs are noncollocated but have the jw axis pole-zero interlacing property possessed by systems under collocated control. The modified outputs offer the potential of giving increased damping in a feedback configuration without introducing the dangerous non-minimum-phase zeros normally associated with non-collocated control. Experimental results are presented which show that it is practical to use these modified outputs.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Read more4Comparative study between PI and sliding mode controllers for flexible joint manipulator driving by Brushless DC motor
In this paper, a comparison between PI and sliding mode control is proposed for the control for flexible joint manipulator driving by Brushless DC motor (BDCM)to improve the performance in the presence of errors in the parameters identification. First, the model of flexible joint manipulator was presented. Then, a PI control is studied and designed for tracking problem of the single flexible joint manipulator. Besides, sliding mode control is studied and designed also for the same problem. Finally, those strategies of control are implemented in the Matlab-Simulink environment to show the high performances and a comparative study of the different strategies of PI and sliding mode controllers was achieved. Although the presence of flexibility in the joint, the simulation results show the high performances of sliding mode controller by converging the error to zero and guaranteeing stability of the robot.
Read morePredictive controller design for flexible link manipulator
The manipulating system of modern high-speed industrial robot may often contain the links with lowered mechanical rigidity. As the result, such a manipulating system possesses the increased level of vibrations and link's deformations under it's own weight and load. This leads to additional trajectory control and positioning error of the manipulator arm. So the control of flexible links manipulator is a complex problem. The control algorithm for the flexible link manipulator is offered for further explores. The algorithm is build with the use of model predictive control technique.
Read moreUnderwater Flexible Manipulator Double-Loop Feedback Control Based on Built-in Binocular Vision and Displacement Sensor
A real-time and effective double-loop feedback control system for underwater flexible manipulators is raised in this paper. The research object is a kind of underwater flexible manipulator driven by McKibben water hydraulic artificial muscle (WHAM) that can grasp, swallow, and disgorge target objects in its interior space. To make up for the lack of flexibility, an underwater flexible manipulator collaborative working strategy is proposed. A more flexible and smaller flexible manipulator is placed inside the flexible manipulator to assist it in performing difficult underwater works. The control system feeds back the position of internal objects through a built-in binocular camera and the working state of the manipulator through displacement sensors. The control system setups including underwater flexible manipulator subsystem, hydraulic drive subsystem, PLC control subsystem, displacement sensor subsystem, built-in binocular vision subsystem, and upper computer subsystem is built. PYTHON-based built-in binocular vision software and C++-based underwater flexible manipulator control software are also developed to facilitate observation and recording. The underwater flexible manipulator collaborative experiment is designed to verify the performance of the control system and the control algorithm.
Read more11Gradient-descent based trajectory planning for regulation of a two-link flexible robotic arm
In the control of flexible manipulators, most work in the literature concentrates on the suppression of link deformations. In this study, the aim is not to suppress the deflections, but to calculate joint angles to minimize the tip position error. A gradient descent method is utilized off-line for the trajectory planning of a two-link flexible manipulator under gravity. Fuzzy logic control with gravity compensation is applied for the position control of the manipulator where the reference inputs are the values of the joint angles as determined by the trajectory planning procedure. Simulations have been carried out to show the performance of both the trajectory planning method and of the fuzzy controller in a regulation problem. Results are illustrated both in the joint space and in the operational space.
Read more10Study on fuzzy PD control of planar two-link flexible manipulator
In this paper, we emphasized on the research of dynamic nonlinear control of planar two-link flexible manipulators. The flexible manipulator is a nonlinear and strong coupling dynamic system, and the complicated control system of which has a bad control property of real time and stability. According to the control problems above, the fuzzy composed controller with a nonlinear compensatory and a PD controller is proposed by well considered both the dynamic and static control properties of the system. At last, the control method is verified by computer simulation, based on the dynamic model of a planar two-link flexible manipulator. The simulation results show that the control strategy has a good result on the elastic vibration reducing of flexible manipulators.
Read more2Dynamic hybrid position/force control of n-link flexible manipulators
In this paper, a method is proposed whereby both contact force exerted by a flexible manipulator, and position of the end-effector while in contact with a surface are controlled. The authors approximate elastic deformations by means of B-spline functions and derive dynamic equations of joint angles, vibrations of the flexible links, and constraint forces. A controller for the hybrid position/force control of the flexible manipulator is designed on the basis of the singular perturbation method. Experimental results confirm that the controller performs remarkably well.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Read moreFuzzy Neural Networks Control of Flexible Robotic Manipulator Based on Lumped Spring-Mass Model
In this research, the focus is on the adaptive fuzzy neural networks (NNs) control of the single-link flexible robot manipulator, which achieves accurate trajectory tracking and improves the speed of position tracking. Firstly, in order to establish a single-link flexible model, the lumped spring-mass method and Lagrangian equation are used. Secondly, a full-state feedback control is proposed. Aiming at achieving the control objective, the Lyapunov stability method proves that the closed-loop system is uniformly ultimately bounded. Finally, Numerical simulations are carried out to verify the performance of the fuzzy NNs control. Furthermore, the control performance is compared with the proportion derivative control.
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